Médecins Sans Frontières (MSF), also known as Doctors Without Borders, which is operating the Aquarius alongside SOS Mediterranne, urged a rethink.
"The prime minister has given instructions for Spain to honour global commitments on humanitarian crises and announced that the country will receive the ship Aquarius", his office said in a statement.
Eric Ciotti, a prominent hard-right MP from the opposition Republicans party, also called on the government to take a tough line on the Aquarius.
It said 40 people were rescued and are being given food, water and medical care on board the ship.
A child looks on as Nigerian Christians pray aboard rescue ship MV Aquarius, off the coast of Sicily on May 14, 2018.
The EU and the bloc's biggest member state Germany made similar pleas.
Mayors in Naples, Messina, Reggio Calabria, and Palermo stood against the poll-topping, recently installed Interior Minister and Deputy Prime Minister Matteo Salvini Sunday after he said the migrant ship Aquarius would be turned away from Italy, reports Italy's Il Giornale.
But Italy's new anti-establishment government, looking to put pressure on the European Union to re-write its immigration rules, showed no signs of relenting despite warnings of an approaching storm bringing waves of over 2 metres (6.5 ft). Salvini retweeted a video with Strada's comments, adding "Stop human trafficking, let's defend our boundaries, I won't give up, my friends".
Production-ready Aston Martin Rapide AMR to launch at Le Mans 2018
Aston Martin says it only plans to make just 210 of the cars to sell worldwide, each priced from $240,000. The Silhouette gets a full-length contrasting stripe in China Grey or Clubsport White instead.
U.S. babies, toddlers consume sugar well beyond recommended levels
The earlier patient is introduces to high sugar consumption, the heavier the consequences he or she will face during the life. Ready-to-eat cereals, bakery items, sugar-sweetened beverages, yogurt, and candy can be major sources of added sugar.
Rising fuel prices spur inflation in May
May was the seventh straight month in which inflation was higher than the RBI's medium-term target of 4 percent. The Federal Reserve on Wednesday is widely expected to raise US rates for the second time this year.
The migrant influx has led to a populist backlash, with Salvini vowing to prevent Italy from becoming the "refugee camp of Europe".
"My aim is to guarantee a peaceful life for these youths in Africa and for our children in Italy", Mr Salvini said, using a Twitter hashtag which translates to, "We are shutting the ports".
Malta's government replied saying Prime Minister Joseph Muscat had spoken to Italian premier Giuseppe Conte and underlined "that Malta is acting in full conformity with its worldwide obligations".
"If we can't rely on getting relief in any of those ports, I personally say we can't go back out" for additional missions, said Klaus Stadler, the captain of a rescue boat operated by the German NGO Sea-Eye. Some of those on board are reportedly pregnant women, and 15 others have serious chemical burns.
The migrants were rescued in six separate nighttime operations in the central Mediterranean on Saturday.
"Given the location of the ship and the urgency, my opinion is that it would be natural to open a Corsican port to help those people in distress", President of Corsican Assembly Jean-Guy Talamoni, tweeted on Monday evening.
The rescue service said its patrol craft reached nine different boats carrying migrants that had left from Africa on Saturday and early Sunday.
Among those on board are 400 migrants rescued by the Italian navy and merchant vessels before being transferred to the Aquarius.
Italy has taken in more than 640,000 mainly African migrants over the past five years.
When 629 people were rescued from drowning they might have expected to be treated with some humanity.